The former CEO of the Rehab Group, Frank Flannery, says the Public Accounts Committee was "totally out of order" to try and question him over its spending.
Mr Flannery says the Rehab Group is not under the PAC's remit, and that this was upheld by the Dáil's procedural committee.
The Committee on Procedures and Privileges rejected attempts to call Mr Flannery and his successor Angela Kearns in for questioning.
Mr Flannery said his connections to Fine Gael were probably the reason he was called in.
He said: "They, for whatever reasons of their own, asked me to come before them and I never refused that request.
"But I did ask them to tell me what matters they wished to question me on and to indicate how that fell within their remit.
"They were never able to answer that question to me."